Download MITOSIS

CELL CYCLE
The life cycle of a cell consists of a
repeating set of events
Phases of Cell Cycle
• Interphase
G1: Normal cell
function
S: DNA Replication
G2: Preparation for
cell division
• M Phase (Red )
Mitosis
Cytokinesis
G1 Phase
• Period of normal cell function
• Cell growth and synthesis of materials needed for
proper cell function take place
• Certain cells never leave G1
Known as G0
Red blood cells, neurons, skeletal muscle cells
These cells will not divide or grow, but will continue to
function until cell death
• Cells which will divide pass through a "point of no
return" and proceed through S, G2 and mitosis.
S Phase
• DNA synthesis occurs.
• Genes copy themselves by the process known
as replication.
Chromosomes consist of two identical strands once
replication is completed. Each of these strands is
called a chromatid.
During mitosis the chromatids will separate and
each chromatid will become a separate
chromosome.
M Phase
• Mitosis: division of the nucleus
Prophase
Metaphase
Anaphase
Telophase
• Cytokinesis: division of cell cytoplasm
Animals—Cleavage Furow
Plants—Cell plate
Timing for a Typical Cell Cycle
• Plants: usually
10-30 hours
• Animals: 1824 hours
• Varies from 20
minutes to
several days or
weeks
• Greatest
variation in G1
See Cell Cycle Animation
Interphase
• Most cells are in
interphase, the phase
between cell divisions.
• The chromosomes are
uncondensed with
their strands existing
as chromatin in the
nucleus. They become
condensed as
chromosomes during
mitosis.
• Label- centrioles,
chromatin, nucleus,
MITOSIS
• Mitosis: the nuclear division of a cell
• Cytokinesis- produces two identical daughter
cells.
• Recognizable phases of mitosis:
Prophase
Metaphase
Anaphase
Telophase
Early Prophase
• Chromosome
condensation –
get thicker
• Nuclear envelope
breaks down
• Centrioles move
toward opposite
poles and pulls
the spindle fibers
with them
Late Prophase
• Chromosomes
very thick
• Nuclear
• Membrane
disappears
• The
centromere
attaches the
chromosome
to the spindle
fibers.
• Do NOT have
to know
kinetochore
Metaphase
• Chromosomes
are aligned at
the equator
and are
attached to the
spindle.
Anaphase
• Individual
chromatids pull
apart..
Telophase and Cytokinesis
Telophase
• Chromosomes
reach the poles
• Nuclear envelope
forms around each
chromosome set
Cytokinesis• Daughter cells
become separated
by cell
membranes.
Cytokinesis and Late Telophase
• Chromosomes de-condense / get thinner
• A nucleolus forms as the cells enter into interphase.
Onion Root Tip: Interphase
Onion Root Tip: Prophase
Onion Root Tip: Metaphase
Onion Root Tip: Anaphase
Onion Root Tip: Telophase
Interphase
Prophase
Prophase
Metaphase
Anaphase
Telophase
Telophase
Which Stage is This?